Quantitative and qualitative colorimetric tests for measuring components of biological fluids are a mainstay of modern medical practice, and are available in different forms, such as dipsticks, treated slides, and reagent solutions in test tubes. The chemical technology of most of these tests is old and in the public domain. For example, reagent tests for the detection of occult blood were developed before the 20th century. Modern colorimetric tests for blood often utilize the same chemical reactions as do the older tests, in which the peroxidate-like activity of hemoglobin catalyzes the oxidation of a variety of leuco dyes (chromogens) to produce a highly distinctive color, thereby indicating the presence of blood.
There are currently several products available for detecting fecal occult blood, incorporating different chromogens and delivery systems. One example is disclosed in U.S. Pat. No. 3,996,006, and is marketed under the trade name "Hemoccult.RTM.". U.S. Pat. No. 2,838,377 discloses a delivery system, using the same technology, for use in a toilet bowl. Other colorimetric tests, such as those for blood and urine glucose, pH, protein, leukocyte esterase, ketone bodies, cholesterol, and toxic substances, use different delivery mechanisms.
Certain applications require specialized delivery formats. One such application is in the analysis of various components of domestic and companion animal urine. Analysis of animal urine can be costly, and obtaining a clean specimen is often difficult, particularly with cats. These factors may dissuade pet owners from having urine tests performed, at the expense of timely and appropriate veterinary care for the animals. Detecting blood in animal urine and feces is one of the most frequently required veterinary tests, since the presence of blood in excreta is an early sign of many disease processes, including urinary and intestinal neoplasms, poisoning, trauma, inflammations, infections, and urinary system calculi. In these conditions, early detection and prompt therapy are necessary to expedite successful treatment.
Feline Urological Syndrome (F.U.S.) is a common cause of hematuria (blood in urine) in cats, affecting 21.5% of all male cats and 13.5% of all female cats. Furthermore, many animals with an episode of F.U.S. suffer a recurrence of the disorder. The mortality rate from the condition is over 20%, from uremia, dehydration, shock, and in some cases, from bladder rupture. If initiated early, treatment is usually successful.